The purpose of this study is to determine differences, assessed in a longitudinal study in bone loss between postmenopausal African American, White, Asian and Native American women, and similar ethnic groups of men ages 55-75 years. Measured differences in the rates of bone loss determined by DEXA will be correlated with blood and urine parameters of bone turnover. Longitudinal data on racial and gender differences in rates of bone loss have not been determined, nor has the relationship of variation in bone mass over time been correlated with commonly used parameters of bone turnover , such as serum osteocalcin, serum procollagen peptide levels, and urine excretion of deoxy-pyridinoline crosslinks. This is a two year study with variation in participants' bone mass measured at three points during ths study. Additional data include a detailed diet history, and anthropometric measurements. Sixty-two subjects have been enrolled to date. An initial analysis based on year one data demonstrated increased bone mass in African American subjects compared to White subjects, but did not show a correlation of bone density with parameters of bone turnover in either African American or White subjects. Only three men have been recruited to this protocol. Significant bone loss was revealed in one male, but not in the two others at one year. Year two data is currently being analyzed. This data will assist in the definition of racial determinants of bone mass in postmenopausal women, and provide insight into the value of measuring serum and urine parameters of bone turnover as methods of bone mineral status in postmenopausal women and older men.